1. Field of the Invention
The present invention relates to a substrate processing apparatus for performing a process, such as a thin film forming process, an oxidation process, a diffusion process, an annealing process, and an etching process, on a substrate such as a silicon wafer.
2. Description of the Prior Art
Examples of substrate processing apparatuses include a single wafer type substrate processing apparatus configured to process substrates one by one and a batch type substrate processing apparatus configured to process a predetermined number of substrates at a time.
A batch type substrate processing apparatus includes a vertical furnace, and a predetermined number of substrates are processed in a processing chamber of the vertical furnace.
A reaction tube defining the processing chamber of the vertical furnace has an opened tube shape and is provided with a heating device disposed around the reaction tube. In the processing chamber, substrates are horizontally held in multiple stages by a substrate holder (boat), and a predetermined process is performed on the surfaces of the substrates by controlling the pressure of the processing chamber to a predetermined processing pressure, heating the processing chamber to a predetermined temperature, and introducing and exhausting a processing gas into and from the processing chamber.
A gas nozzle used for supplying a processing gas to the processing chamber is erected along a wall of the reaction tube, and a temperature detector used for detecting the temperature of the processing chamber is also erected along the wall of the processing chamber.
In the related art, the gas nozzle and the temperature detector are installed in a manner such that the gas nozzle and the temperature detector are inserted horizontally through a lower part of the reaction tube, bent upwardly in a vertical direction, and extended along the wall of the reaction tube.
FIG. 14 illustrates a supporting structure for a gas nozzle and a temperature detector of a conventional substrate processing apparatus.
A reaction tube 1 is installed coaxially with a short cylindrical inlet flange 2, a seal such as an O-ring 3 is disposed between the inlet flange 2 and the reaction tube 1, and a joint between the reaction tube 1 and the inlet flange 2 is securely sealed. The inlet flange 2 is supported by a structural member 4 such as a top plate of a loadlock chamber, an O-ring 5 is disposed between the structural member 4 and the inlet flange 2, and the inlet flange 2 and the structural member 4 are air-tightly joined.
A lower opening of the inlet flange 2 forms a furnace throat 6, and a boat 7 is loaded into and unloaded from a processing chamber 8 through the furnace throat 6 by a boat elevator (not shown). After the boat 7 is placed in the processing chamber 8, the furnace throat 6 is air-tightly sealed by a seal cap 9.
In FIG. 14, reference numeral 11 denotes a gas nozzle, and reference numeral 12 denotes a temperature detector.
In the temperature detector 12, a plurality of thermocouples are inserted in a protective tube made of a material such as quartz. Thermocouples are supported in the protective tube at different heights so as to be used for detecting temperatures of a plurality of positions inside the processing chamber 8. The gas nozzle 11 is configured by a tube such as a quartz tube.
Both of the gas nozzle 11 and the temperature detector 12 are configured such that vertical loads acting on parts of the gas nozzle 11 and the temperature detector 12 inserted through the inlet flange 2 are supported by narrow tube supporting members 13 and 14.
The narrow tube supporting members 13 and 14 have the same structure, and thus only the narrow tube supporting member 13 will be explained in the following description.
An inner flange 15 protrudes from a lower inner surface of the inlet flange 2 toward the center of the inlet flange 2, an adjustment bolt 16 is inserted through the inner flange 15 in a vertical direction, and the adjustment bolt 16 is fixed by a lock nut 17. At an upper end of the adjustment bolt 16, a nozzle receiving flange 18 is installed, and the nozzle receiving flange 18 is configured such that the center of the nozzle receiving flange 18 is brought contact with a leading end of a horizontal part 11a of the gas nozzle 11 from the bottom side of the leading end of the horizontal part 11a. 
Furthermore, at the horizontal part 11a, a flexible seal ring (not shown) is fitted, and a fastener such as a nut is used to press the seal ring against the horizontal part 11a, such that a penetration part of the horizontal part 11a can be air-tightly sealed and the horizontal part 11a can be fixed to the inlet flange 2 by the pressing force of the nut.
In the conventional substrate processing apparatus, the supporting structure for the gas nozzle 11 and the temperature detector 12 is required to support the gas nozzle 11 and the temperature detector 12 along the inner wall of the reaction tube 1 to prevent falling of the gas nozzle 11 and the temperature detector 12.
Therefore, the height of the nozzle receiving flange 18 is adjusted in a manner such that a vertical part 11b of the gas nozzle 11 can be positioned vertically along the inner wall of the reaction tube 1.
However, if the inside of the reaction tube 1 is decompressed, a compressing force is applied to the O-ring 3, and thus the O-ring 3 is compressed. In this case, if the O-ring 3 is not uniformly compressed along its circumference, the reaction tube 1 inclines with respect to the inlet flange 2.
Accordingly, a horizontal load is applied to vertical parts of the gas nozzle 11 and the temperature detector 12 that are installed along the inner wall of the reaction tube 1, and thus penetrated parts of the inlet flange 2 can be damaged.
Furthermore, if the inside of the reaction tube 1 is decompressed, horizontal forces are applied to horizontal parts of the gas nozzle 11 and the temperature detector 12 in a direction toward the center of the reaction tube 1, and since parts of the horizontal parts inserted through the inlet flange 2 are fixed by friction, the gas nozzle 11 and the temperature detector 12 can be inwardly slid. This causes problems in that the vertical parts of the gas nozzle 11 and the temperature detector 12 are dislocated away from the inner wall of the reaction tube 1 and are thus supported in an unstable state.